It is known in the art of vermin and pest control that such vermin or pests as rodents, cockroaches and insects, e.g., mosquitos and flies are very sensitive to ultrasonic vibrations. Such ultrasonic vibration of sufficient intensity and duration can affect the nervous system of such vermin and pests and eventually cause disabling or mortal effects. As a consequence, when exposed to such ultrasonic vibrations these vermin and pests either attempt to avoid them or suffer the other consequences.
In the present art of ultrasonic generators, particularly of the kind used for pest control, a transformer with a rectified output is used to provide a DC voltage to a 555 integrated circuit of the kind manufactured by RCA arranged as an astable generator. The output on pin 3 of such an integrated circuit is employed to drive a piezoelectric transducer connected mechanically to a speaker to produce ultrasonic vibrations. Such a piezoelectric transducer and speaker cone may be of the type made by Motorola as a model KSN 1038A or KSN 1041A.
By connecting pin 5 of the 555 integrated circuit to the low voltage side of the transformer, the prior art circuit results in a sweep of the output square wave frequency over a narrow range.
Vermin and pests of the type noted above appear to be susceptible to sweeping of the ultrasonic frequency, and the greater the sweep the greater the detrimental effect of the ultrasonic frequency sonics on the pest. In addition, sweeping the frequency randomly prevents the pests from becoming acclimated to the ultrasonic frequency, which would detract from its pest control effectiveness. Further, pulsed bursts of ultrasonic frequency appear to be very effective for pest control.
The prior art devices which employ a transformer in the power supply require the bulk, weight and expense of a transformer. In addition, when considering a unitary design for the United States and Europe, this cannot be effected with a single transformer because of the difference in AC voltage between, respectively, 110 VAC and 220 VAC and different frequencies of from, e.g., 25 Hz to 60 Hz. Further, a transformer creates a great problem in heat generation during operation, which can create a danger when the ultrasonic apparatus is used for pest control and placed in remote and unairconditioned spaces, e.g., an attic.
An additional consideration is that the ultrasonic devices of the prior art are output limited to about 125 db which inhibits somewhat their effectiveness. The piezoelectric transducer is also driven continuously, creating further heat generation problems.
There is also a need for a small, light-weight speaker (transducer) which is efficient at the ultrasonic, as opposed to audio, ranges, which is easy to manufacture and inexpensive in cost.
It has also been a problem with prior art ultrasonic vibration generators of the kind used for pest control that they tend to emit some sound in the audio range. This can be very distracting in habitat and work areas.
The problems enumerated in the foregoing are not intended to be exhaustive, but rather are among many which tend to impair the effectiveness and usefulness of known ultrasonic vibration generators, and their use for vermin and pest control. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that prior art ultrasonic vibration generators used in the past, and their use for vermin and pest control have not been altogether satisfactory.
Recognizing the need for a better ultrasonic pest and vermin control apparatus and a cheaper and more effective means for generating these ultrasonic vibrations, it is a general feature of the present invention to provide a novel ultrasonic vibration generator.
It is a further feature of the present invention to provide a cheaper and more versatile ultrasonic vermin and pest control apparatus which requires no input transformer, thereby eliminating all of the attendant problems caused by having an input transformer.
It is a still further feature of the present invention to provide a novel and more effective means for varying the ultrasonic output in order to control pests by generating periodic bursts of ultrasonic frequency and sweeping the ultrasonic frequency during each burst, in a manner which preferably differs from burst to burst.
Another feature of the present invention is a novel means of significantly reducing the audio sound output during ultrasonic vibration generation.
Still another feature of the present invention is a speaker means which increases the efficiency of producing ultrasonic vibrations without a significant change in the cost, size or configuration of presently used speakers.
An ultrasonic vibration generator according to presently preferred embodiments of the present invention, and intended to substantially incorporate the above-noted features, includes a transformerless pulsed sweep ultrasonic generator. The ultrasonic generator of the present invention is capable of producing a low duty cycle pulsed sweep of ultrasonic vibrations from about 25 KHz to 55 KHz with no input transformer. Also, the apparatus of the present invention can produce about 100 times the ultrasound level of similar known ultrasonic generators, i.e., about 150 db.
A cascaded voltage doubler supplies output DC voltage to a CMOS integrated circuit of quad 2 input NOR gates, one half of which acts as an astable multivibrator and the other half of which acts as a duty cycle generator for the one half, the duty cycle of which and the oscillating frequency of which are determined all in accordance with external circuit components connected to the pins of the integrated circuit.
The output of the integrated circuit controls a VMOS power amplifier which includes a ringing circuit that is gated by the VMOS in response to the output pulses from the astable multivibrator during each burst of multivibrator output pulses, which creates a relatively large, 80 V peak-to-peak, voltage to a mechanical transducer, e.g., a piezoelectrical crystal transducer, at a swept ultrasonic frequency. The transducer is mechanically connected to a throatless free-floating speaker. The net effect is one of having a transformerless swept tone burst generator in the ultrasonic range with, in addition, a more efficient speaker arrangement.
Examples of the more important features of the present invention have thus been summarized rather broadly in order that the detailed description that follows may be better understood, and in order that the contribution to the art may be better appreciated. There are, of course, additional features which will be described hereinafter and which will also form the subject of the appended claims. These features and advantages of the present invention will become apparent with reference to the following detailed description of preferred embodiments in connection with the accompanying drawings, wherein like reference numerals have been applied to like elements.